tiffin 2014 bus air gauge
Welcome to iRV2!!
It would be helpful to provide more information about your coach e.g. model, engine, chassis, etc, in your signature.
Just a minor suggestion - if your gauge looks like this then besides the important points already made by Gary, if you haven't done so you should also check to make sure the gauge has been properly "reset" by pushing the yellow button on the bottom.
Or the gauge itself could be faulty...
Hugh & Judy with Golden Retrievers Lars, Kenzie & Arvy in 2009 Triple E Invitation 40' QSDP, FL-XCR, Cummins 8.9L ISL 400HP, Allison 3000MH towing 2009 Jeep Liberty